The number and variety of medical methods available to repair the effects of cardiovascular disease has increased rapidly over the last several years. More particularly, alternatives to open heart surgery and cardiovascular by-pass surgery have been extensively investigated, resulting in non-surgical procedures such as percutaneous transluminal coronary angioplasty, laser angioplasty, and atherectomy. These procedures are primarily directed toward the reduction of stenosis within the vasculature of a patient by either expanding the lumen through the use of a balloon, or ablating or otherwise removing the material making up the stenosis.
While these procedures have shown considerable promise, many patients still require bypass surgery due to such conditions as the presence of extremely diffuse stenotic lesions, the presence of total occlusions and the presence of stenotic lesions in extremely tortuous vessels. Also, some patients are too sick to successfully undergo bypass surgery, and because the above treatments require surgical backup in the case of complications, they are untreatable. Some patients requiring repeat bypass surgeries are also untreatable.
One alternative to these procedures is known as Laser Myocardial Revascularization (LMR). In LMR, channels are formed in the ventricle wall with a laser. These channels provide blood flow to ischemic heart muscle. A history and description of this method is presented by Dr. M. Mirhoseini and M. Cayton in "Lasers in Cardiothoracic Surgery" in Lasers in General Surgery (Williams & Wilkins; 1989) pp. 216-223.
In the procedure described therein, a CO.sub.2 laser is used to produce channels in the ventricle from the epicardium through to the myocardium. This procedure follows a surgical cutdown. External pressure is used to stop bleeding from the ventricle to the outside. Dr. Mirhoseini has documented that although the channel is sealed at the epicardial layer, it remains patent in the endocardial and myocardial layers. Laser energy is transmitted from the laser to the epicardium by means of an articulated arm device that is commonly used for CO.sub.2 laser surgery.
A proposed improvement in the design is described in Hardy--U.S. Pat. No. 4,658,817. A needle is added to the distal tip of the articulated arm system, with laser energy passing through the lumen of the needle. The metal tip of the needle of the device is used to pierce most of the myocardium and the laser beam is used to create the desired channel through the remaining portion of the myocardium and through the adjacent endocardium.
Hardy contends that mechanical piercing serves to facilitate sealing of the epicardial portion of the channel. Mechanical piercing is highly undesirable, because such piercing always entails some degree of tearing of the pierced tissue. Tearing leads to fibrosis as the mechanical tear heals. Fibrosis severely diminishes the effectiveness of the LMR treatment.
These LMR procedures still require that the chest wall be opened in order to access the heart muscle with presently utilized laser devices. Thus these procedures require major surgery which is highly invasive and which may result in severe complications.
An additional problem associated with those procedures utilizing an articulated arm device is that the articulated arm is difficult to manipulate. Thus portions of the heart may be effectively unreachable by the device.
Broadly, it is the object of the present invention to provide an improved method for performing laser myocardial revascularization.
It is a further object of the present invention to provide a less invasive method for performing laser myocardial revascularization.
It is a still further object of the present invention to provide a method for performing laser myocardial revascularization which can access difficult to reach portions of the heart.
It is a yet further object of the present invention to provide a method for performing laser myocardial revascularization which does not require mechanical perforation of heart tissue.
These and other objects of the present invention will be apparent to those skilled in the art from the following detailed description and the accompanying drawings.